Answer:
We have an inequality triangular theorem that "If ABC is a triangle, then AB+BC >AC, AC+BC >AB and AC+AB>BC i.e. the sum of any two equal sides of a triangle should be greater than the third side.
We will use same theorem here:
Lets take the first choice, A:
8 , 10 and 18. Here we see that 8 +10 > 18 is incorrect. Therefore, the triangle with side length of 8, 10 and 18 doesn't exist.
Take another choice, B:
8, 10 and 7
Here, 8 +10 > 7, 10+7 >8 and 7+8 > 15. Therefore, option B is the correct answer.
You can use the same theorem in other options.
